Different Worlds
by AngryComet48
Summary: The sequel to "The Story of Sonic the Hedgehog". Sonic and Tails stumble on Sora, Donald, and Goofy, who've crashed on Mobius! Also, Knuckles must fight the Heartless who've invaded the world in search of the keyhole!
1. Mobius Lost

**Welcome ladies and gentlemen, to the sequel to The Story of Sonic the Hedgehog! This story occurs a few years later, and will also be my first crossover, so this should be interesting! Enjoy!**

Ages:

Sonic the Hedgehog: 16

Tails the Fox: 13

Amy Rose the Hedgehog: 14

Knuckles the Echidna: 16

Rouge the Bat: 18

Shadow the Hedgehog: Who knows?

Chapter 1: Mobius Lost

-Sonic's POV-

"Come on Tails! You can do it!" I encourage my brother, running just below the speed of sound. "You're almost there!" I smile, running alongside him, remembering how determined he is to run as fast as I. I look over to see him looking tired, yet with energy in his eyes. Suddenly his twin tails start rotating faster, propelling him at a higher speed when suddenly, he shatters the sound barrier with a deafening sonic boom.

A few minutes later, Tails, breathing heavily decides to ask me a question. "How... do you run... that fast... and not get... tired?"

I think for a few seconds before answering. "Well, to be honest, I'm not really sure. I mean, I guess I was just born with it. Maybe you'll be able to do the same soon too." I notice a shooting star. "Hey look! A shooting star Tails! Maybe you can wish for more stamina, you slow poke!" I tease, to which I recieve a light punch to the arm.

"Fine." Tails gets up and closes his eyes. I look back at the star to see it got bigger. Tails opens his eyes. "Huh? That looks bigger... Wait a second! It's coming towards us!"

I grab Tails' arm and pull him to safety. We watch as the "star" zips right by us and crashes into a nearby field. "C'mon! Let's go check it out!" I say excitedly, before dashing off with Tails right behind.

We reach the impact site to find our view obstructed by smoke coming out of the small crater. I run around the crater at a high speed, creating a vacuum to cool and get rid of the smoke. I hear Tails gasp, and I look. My eyes widen when I realize that instead of a asteroid, it's some kind of space ship. Tails and I walk into the crater and up to the ship. I lightly tap the glass of what looks like the cockpit.

"Hello? Anyone home?" I ask. Without warning, I hear a hiss. I jump back as the cockpit slowly opens, letting a lot of steam out.

"Ack!" I hear someone say. "Get me out of here! It's so hot!" A brown hedgehog with wearing yellow shoes, fingerless gloves, and a black and white jacket hops out. Following him, a white duck with a blue shirt hops out, along with a black dog wearing a green turtleneck and orange pants. The duck and dog start inspecting the ships damage while the hedgehog turns to Tails and I.

"Hello there, who might you be?" He asks. "I'm Sora." He points at the duck then the dog. "That's Donald and Goofy."

"I'm Sonic." I reply. "Sonic the Hedgehog."

"Now, this may seem like a strange question, but where are we right now?"

"This is Emerald Hill Zone, on planet Mobius." Then something clicks in my mind. "Wait, are you guys from a different planet?"

"Well, I guess so..." I notice that he seems uncertain about how to answer my question. "We kind of crashed here on accident, but while we're here," He trails off.

The duck known as Donald approaches Sora. "It'll be a while before we can leave. We might as well try to find the keyhole."

"Keyhole?" I hear Tails ask. "What do you mean by that?"

"A keyhole," Goofy begins. "Is like the doorway to the heart of the world, right Donald?"

"Right."

"And Sora here needs to seal it, or your world here could disappear."

Sora nods. "I seal it with this." He holds his hand out in front of him and summons what appears to be a giant key. "This is the keyblade."

Tails' eyes seem to almost pop out of head. "Woah! Did you just make that appear out of thin air?!"

"Yep."

Suddenly, we hear a beeping to find it's coming from Tails' wrist communicator. It's Knuckles.

"Guys, come to the Master Emerald quickly!" I find myself surprised at the amount of panic in Knuckles' voice. "It's under attack!"

"We'll be right there!" I assure and Tails turns his wrist communicator off. I look at our new friends. "Sorry about this, but that's our que." Then Tails and I rush off at top speeds, clearly leaving the trio in awe.

Less than a minute later we arive at Tails' workshop, hop in the Tornado, then take off towards Angel Island. As we're flying, I notice a strange purple fog coming from the direction of Angel Island. "What's that?" I ask Tails.

"I have no idea, but it can't be good."

I nod, knowing that something big is coming. I continue to watch for our friend's island, and around four minutes later, we arive. I hop out, along with Tails, and start running towards the barely visible green glint through the fog.

We reach the stairs to find that they're destroyed. I look over at Tails, who nods, and he grabs my hands and starts pulling me up to the top. When we reach the top, I feel Tails almost drop me as we see the startling sight. The Master Emerald is not in its hole, Knuckles is fighting black creatures that come from seemingly no where, and the Master Emerald's hole has a golden light shooting out of it.

I jump down to help Knuckles fight off the creatures. "They won't stop coming!" He says as he punches one, causing it to burst into a black cloud, then fade away. "They're after whatever's in that hole!" I charge up and spin dash a line of them, but more appear in their places. I look up to see Tails blowing the fog away from the platform with his tails.

"Good job Tails!" I call out when I see the fog cleared enough to see around better. I turn around to see a creature in the air, about to land on me, but I jump up and kick it. "Knuckles!" He pauses fighting and looks. "I'm going to see where this light is coming from!" He nods and punches through a creature about to bite him. I turn to the hole and hop down into it, to find the light is coming out of a keyhole on the bottom. Out of curiousity, I look into the keyhole directly through the light. I can't see anything through the light.

"Sonic! Help me!" I hear Tails scream.

"Tails!" I yell, and I hop back up. There, covered in those black monsters, I can barely see Tails' terrified face. I jump over to him and spin kick all of the monsters into oblivion.

"S-Sonic... H-help me..." I look over at him and gasp at his glowing chest. The glowing gets brighter, until what appears to be a heart made of crystal comes out of my brother. My eyes widen as I watch the heart floating into the sky. I look down to see Tails' body fading into darkness. I clench my fist.

"Tails..." I start to feel raw power surging through me. "I will save you. And I will kill them all." My emotions turn into nothing but anger, as I feel myself get stronger. I barely feel the tears trickling down my muzzle as the transformation is completed.

-Knuckles' POV-

I look up from my struggles with the things to see Sonic's blue fur turn black, his quills bend upward, and his pupils disappear. Dark Sonic is here. I jump out of the way, knowing that when Sonic's like this he'll destroy whatever's in his way. As if on cue, Sonic flys back and forth faster than I can tell, and all of the creatures are gone. I notice a monster hobbling over to the hole, and I watch it jump down into it.

_Wierd... How did Sonic not get that one? _I wonder. Suddenly, the golden light stops, as well as Sonic. I look over to see that his fur is once again blue and that he's on his knees. Not wanting to mess with him after whatever made him so mad, I investigate the hole. I look and see a purple keyhole fading away. _That's odd. I wonder if that thing did that..._

"They took him." I look over at Sonic. "He's gone now, by best friend, my-" He breaks down into sobs. I almost fall over when I realize what he's talking about. Tails is gone, and from the sound of things, dead.

I lose my balance and fall on my rear end when the ground starts shaking. I look over at Sonic, who doesn't seem to notice. I look up and see a giant black ball sucking up bits and pieces of our world. I hop up and hold down the Master Emerald, but it gets pulled up into the ball, and drags me along with it.

**Wow. That was dark, pun intended. Anyway, I hope you enjoy, and as you can tell, this story will probably be a lot darker than the other. Please R&R, and I'll see you all next time!**


	2. Amnesia

**Hello once again everybody, and welcome, to... Chapter 2! Sorry for the wait, but writing takes time. :P**

**Disclaimer: I do not own Kingdom Hearts or Sonic the Hedgehog.**

Chapter 2: Amnesia

-Sonic's POV-

I slowly start to wake up with a dull pain in my head. I keep my eyes closed and try to remember what happened, but to no avail. Annoyed with my failure, I open my eyes and stand up to find that I'm in an alley. I look around and spot a sleeping red echidna sitting not far off. With no other ideas, I go over to him and start shaking him awake.

"Hey! What's the big-" He stops when he notices me. "Sonic? Sorry about that..." He looks around. "Where are we?"

"I don't know." I respond. "And who's Sonic?" He starts laughing, then stops when he sees my genuinely confused face.

"Wow, you really do have amnesia, don't you?" I cock my head.

"Amnesia? That would explain why I don't remember much of anything..." I think a little harder, but stop due to my headache. He stands up slowly, then stretches his muscles.

"Let's go find out where we are." I nod and follow him. We step out of the alley and take a look around. We go down some steps and see a group of kids playing. One of them sees us, then all the others turn and look. They appear to forget what they're doing, then they quickly run and hid in a house.

"Um... I don't think we're welcome here, whatsyourname..." I say quietly.

"Knuckles. Thats my name."

"Oh, okay." I nod.

"You can still run, right?" He asks me. I shrug and run over to a lamp post. I look back and see him slowly shaking his head. "Appears you forgot how to run at supersonic speeds..." I hear him mumbling.

"Hey! Sonic over here!" I turn towards the voice, assuming that's my name. I notice a kid with brown spikey hair, a black and white jacket, a red jumpsuit, and yellow shoes. He walks over to me, and I step back from the stranger. "Sonic?"

"He has amnesia." Knuckles simply states. "Probably from the way we got here." The boy nods.

"Bad news about that, by the way. You're world is gone, I'll tell you guys more about that at the cafe." He points, and all three of us go there.

A few minutes later, we finish talking. "So my name is Sonic, I'm some kind of hero, and I can run faster than sound?" Knuckles nods. "And my world is gone?" Sora nods. "This sounds absolutely crazy, but I'll go with it for now." Knuckles and Sora facepalm while I shrug.

"Sora!" I look over to see a duck running towards him. I blink and also see some kind of dog running towards him as well.

"G'warsh, we were so worried about ya, Sora!" The dog says. "I thought we lost ya when you didn't make it to the Gummi Ship in time..."

"I'm fine guys, calm down a little!" He smiles, then frowns. "Do we have any more space in the ship?" Donald shrugs.

"We might be able to ask Cid if we can add some, but why?"

"I think we should bring them," He gestures at Knuckles and I. "Along with us. After all, we might be able to restore Sonic's memory." The duck walks over to me, grabs my hand, and starts shaking it rapidly.

"I'm Donald Duck! And that's Goofy over there! Nice to re-meet you!"

"Uh... Thanks?" I pull my hand away from Donald's, who turns to Sora.

"If we can probably fit two more seats, but that's it. We won't be able to fit anymore." Sora nods, and Donald goes to see Cid, whoever that is.

A couple of minutes later, a man with blond, spiky hair informs us that the changes are done and that the ship is ready. Knuckles and I follow Sora, Donald, and Goofy to the ship outside of town, where we all climb in.

"Just barely enough room for everyone to fit comfortably..." I hear Donald say to Sora. I hear the engines start to power up and a memory comes back.

_I look around and notice that I'm high in the sky sitting in the passenger seat of a bi-plane. I see written in white the word Tornado on a wing. "Hey Sonic?" I turn to the pilot, who's facing me. It's a yellow fox with blue eyes and two tails._

_ "What is it Tails?" I respond, getting the idea out of nowhere that's his name._

_ "Is it just me, or has Knuckles been kind of distant lately?"_

_ "That's Knuckles for ya, he always kind of seemed like the loner type." I assure. "Although, I probably wouldn't hurt to check on him..."_

My eyes snap open to see Knuckles and Goofy staring at me. "What?" I ask.

"Um..." Knuckles slowly begins. "You were just talking to yourself... about me." My eyes widen.

"What did I say?"

"You said something like 'That's Knuckles for ya, he always kind of seemed like the loner type.' I grin sheepishly at hearing this.

"Sorry 'bout that... I remembered something..." Knuckles turns away and stares off into space, probably forgeting the awkward moment. I also notice that Goofy has gone back to do whatever he was doing before.

_Tails... _I think to myself. _I wonder where he went... Well, whoever he is, at least I remember the Tornado. _I feel another memory trying to return, so I close my eyes and let it through.

_I see a pink hedgehog holding on to me and sobbing, while Tails mouths "Sonic's got a girlfriend!" A couple times. I scowl at him and try to comfort the pink hedgehog._

_ "Uh... Amy? Look, if it makes you feel any better, you can come with me and Tails to find Eggman." To my surprise, she stops crying at once and let's go of me._

_ "Do you really mean it? I nod, and she frowns. "Wait, who's Tails?" She asks, causing Tails and I to facepalm._

I open my eyes again after this flashback occurs. To my surprise, no one is paying attention to me. I smile, assuming that I didn't say anything.

A few minutes after I see a large, round, and dark object coming into view. "Welcome to Halloween Town!" Sora says. As we get closer and closer to the world, I notice everybody transforming slowly. Sora's clothes turn a darker color, a pumpkin shaped mask appears covering his right eye, and he gets vampire teeth along with bat wings. Donald transforms slowly into a mummy, while Goofy gets claws and a giant bolt appears on his head. I look over at Knuckles and gasp, seeing how he's turning a slight shade of dark green, his shoes gaining spikes at the end, bandages appearing all over his arms, and his purple eyes turning a bright red.

"Hey Knuckles," I say. "Why don't ya take a look at yourself with a mirror." Knuckles looks around, confused, for something reflective. Donald hands him a highly reflective cube.

"What the?! What's going on here?!" I start to laugh but stop quickly as I realize that my voice got deeper. Knuckles hands me the cube and I inspect myself with it. I see that peach fur on my muzzle has turned blue, my arms are covered with fur, my hands are now claws, my shoes have spikes on the bottom, and to top it all off, my teeth have all turned razor sharp.

"Why are we all changing?" I ask.

"It's because worlds can sometimes have different effects on people." Sora explains. "For example, when we crashed on your world, I turned into a hedgehog."

"But you're human, right?" Asks Knuckles. Sora nods. "Then I wonder why Doctor Eggman didn't transform like you did..." He sees the trio make a confused face. "Eggman was a human scientist that terrorized our planet." He explains. "Yet he stayed human..." Sora shrugs.

"Maybe it doesn't affect everyone?" Sora suggests. With a light bump, I feel us land. The cockpit hatch opens and we all hop out...


	3. Faker!

**Hello everybody! And welcome to chapter 3! I'm sorry for the long delay(life happens), but now I'm back and inspired, and hopefully this won't be very short.**

**Disclaimer: I do not own Sonic the Hedgehog or anything. Just the stories.**

Chapter 3: Faker!

-3rd Person-

A tall, dark castle looms agains a cloudy and sky. A dark figure stands on the castle's highest peak, when lightning illuminates the creature and the sky. The creature is shown by the lightning to have white chest fur, hovershoes, and white gloves. The creature jumps down and lands in front of a doorway, facing away from it.

"You know... the lightning is dangerous. Perhaps you should come inside the castle." A tall and dark robed woman says through the open doors.

"I prefer to be by myself. Not with your goons." The gloved form responds in a deep male voice. He turns towards her and crosses his arms. "And anyway, you still have to tell me about my past."

"All in due time." The woman reassures. "But I will tell you something important that could make you decide whether or not to join us." The creature cocks his head. "Your name is Shadow the Hedgehog." Shadow steps back, clearly rattled by the information, with lost memories returning.

"What the..? I remember who I am..." Shadow stares into space. "Maria..."

-Shadow's POV-

_ I hold on tightly to Maria's arm as we run through Space Colony Ark. I can hear bullets hitting everywhere except for us. I look back and see military personel chasing us, gaining every second._

I blink, coming back to the present. I notice the woman holding a yellow gem of some sort towards me. "Take this." She commands, to which I obey.

"A Chaos Emerald..." I gasp, feeling its raw power. I look up at her. "Fine."

"Fine?" She asks, with obvious sarcasm.

"Fine, I'll help you guys," I say, walking through the doorway and past the woman. I smirk and look back at her. "Malificent."

-Sonic's POV-

Our party of five walks up to a gate, which opens up as if it knew we were going to be there. "Creepy..." I comment.

"We should take you guys to see Jack Skellington," Donald states. "If you thinks that's creepy, he'll really scare ya."

"We'll need Jack's help anyway if we want to find the keyhole." Sora reminds Donald.

"Then on to the professor!"

I look at my surroundings and notice how much this place looks like a town, yet with Halloween's spookyness included. We continue walking until we reach a wall with a door in it. Sora pushes it open, and we all walk inside. Inside, it resembles some kind of courtyard, with stairs leading into a building. We go up and Sora knocks on the door.

"Who is it?" I hear a muffled voice yell.

"It's Sora!" Sora yells back.

"Come in!" Sora opens the door and we all gasp at the sight. Tied to a table and gagged is a pink werehog girl, with some kind of monster scientist standing over her. "Hey guys, you'll never guess where I found this interesting specimen." The professor coughs, then sees me. "Woah! Is that another one?! Where did you find this one?" The other werehog's eyes widen when she sees me. I instantly notice tears trickling down her muzzle.

"Hey, what're you doin' to her?" Goofy asks, perplexed.

"Just some simple experiments, fur samples, heat tests, lighting testing, basic stuff really... Why?"

"Because she's our friend!" Knuckles yells and jumps at the scientist. I catch him just before his fists make impact.

"Can you please just let her go?" I strain, trying to contain Knuckles, who's struggling against my grip.

"Sure I guess, why not?" He responds, while pulling a lever. "She hasn't been the most cooperative anyway..." The table rotates 90 degrees, allowing the girl to slide out of her ties. She rips the gag of and glomps me in an embrace that causes me to drop the now calmed Knuckles.

"Oh Sonic!" She buries her face into my chest fur and starts crying. "It was terrible! I was poked and prodded and zapped and it was scary!" As the whole ordeal occurs, I work on her name.

_Sally? No... _I think. _Ally? Nope... Cindy... Nah. Amy? There we go! That's it!_

"It's okay, Amy." I gently pat her back, somewhat calming her down. A few seconds later, she pulls away and grins sheepishly, noticing my soaking wet fur.

"Sorry..." She apologizes. I give her a small, reassuring smile.

"Don't sweat it."

-Knuckles' POV-

I stand there, with my arms crossed, observing the scene as it plays out before me, when a sudden question pops into my head.

"What happened to your dress?" I blurt, not thinking about the weirdness of such a question. Amy turns to face me with a puzzled look on her face.

"I honestly have no idea. I just woke up with spiky versions of my red boots on and that's it." She then blushes at the sudden realization of my question. "And the fur works just as good as clothing, for your information!" She crosses her arms and closes her eyes, with an annoyed scowl. I blush as well and facepalm, cursing myself for asking about something stupid without wording it better.

"Anyway..." Sora starts, trying to break the awkward silence. He turns to the professor. "Do you happen to know where Jack is?"

"Sure, he's waiting for you guys at the entrance to Oggie Boogie's lair."

"Thanks!" And with that, Sora, Donald, and Goofy walk out to look for Jack.

The professor scratches his head.

"I'm going to go now, you're welcome to stay here in my lab, as long as you don't break anything." He rolls out on his wheelchair.

Amy turns to Sonic.

"By the way, is Tails here with you guys? I just realized he isn't present."

"Tails..?" Sonic starts before I can step in.

"Yes, TAILS. You know, your sidekick, sworn brother, best friend. Please don't tell me you forgot who he is or something."

"Unfortunately, he did. He's got amnesia." I explain everything that has happened, including Mobius' disappearance.

"Yikes!" Amy exclaims. "So these Heartless whatevers are trying to destroy everything? Weirder than Eggman-"

A large crash causes Amy to stop in mid sentence. We run out to the town square to see smoke coming from a crater. A figure jumps out of it and lands with its back facing us.

-Sonic's POV-

The figure slightly turns its head, revealing a familiar face to me. I clutch at my head as a dream returns.

_ I run towards a bridge at top speed hoping that whatever is behind me doesn't catch up. I look back and realize that whatever's chasing me can run at the same speed, if not faster. I stop running and turn around._

_ "All right! That's enough!" I yell. "Who do you think you are, and why are you chasing me?"_

_ Out of some black fog I see a figure walk out. The figure I see is a hedgehog, looking exactly like me except for the fact that instead of having blue fur and spines, its spines and fur are pitch black. "I am the ultimate life form, Faker." It declares, then pulls out a Chaos Emerald. "Chaos Control!" It yells and everything turns white._

"You." I growl. The figure pulls out a yellow and glowing gemstone, which turns me back to normal. Knuckles changes back too, and Amy changes with her dress back. "I found you Faker."

"Faker? Who are you calling Faker, Faker?" He sneers. "You're comparing yourself to me? Hah! You're not even good enough to be my fake."

"I'll make you eat those words!" I yell, and on instict, I curl into a ball and spin at him. I hit a wall and stand, seeing that he jumped over me. He runs to me and punches me square in the face. With lightning fast reflexes, I spin my legs around, kicking him. He falls back. As if in sync, we both curl into a ball at the same time and roll into each other, knocking the other back. He recovers quicker than I and jumps to the top of a fence.

"I'm sorry Faker, but I have a bigger fish to fry." And with that, he jumps off the fence and out of sight.


End file.
